1. Field of the Invention
This invention relates to the sandblasting of a flat sheet of fiberglass composite to produce a sign, the sheet being masked in selected areas. A nickel or copper continuous strand mat could be included in the laminate structure of the composite and exposed during the sandblast operation if it is desired to install the sign in a submerged marine environment.
2. Description of the Prior Art
As disclosed in U.S. Pat. No 2,345,942 entitled "Wood Finishing", it is well known to use wood as a material for making sandblasted signs.
The pattern of the sign is selectively created in the wood surface by the use of a protective surfacing mask laid over the areas of the sign that should not be eroded by the impingement of the sandblast material, such as is disclosed in U.S. Pat. No. 4,702,786. As disclosed in this patent, the surfacing mask may also remain upon the wood surface after the sandblasting operation is completed, to form the exterior of the pattern.
Wood, of course, deteriorates rapidly when placed in an outdoor environment and plastic may be used as a sign material, as disclosed in U.S. Pat. Nos. 4,133,919 and 3,751,319, as well as Japanese Patent 00260905, (No. 50-101822). For example, the '319 patent discloses the fabrication of signs and other artwork that are made with a clear facing layer of polyester resin protecting one or more colored pattern layers. The pattern layers are applied by silk screening after the facing layer has cured to at least a tack-free condition. At the rear surface of the sign is applied a background layer of polyester resin and a stiff glass fiber backing layer. Japanese patent JA-4716336-Q discloses a method of selectively sandblasting a surface of a metal or a synthetic resin molding, whereas the '919 patent teaches sandblasting the surface of a glass or plastic sheet having rubber masking material thereon.
In Japanese Patent 52-26095 a plastic film is applied over a metal or plastic base material and thereafter selectively removed to expose the base material to a sandblasting operation.
Sandblasting may also be used in commercial structural applications, such as discussed in U.S. Pat. No. 4,612,737, wherein a sound attenuation product is produced by attaching a prepared maskant having a desired perforation pattern to a cured contoured or flat composite material. A narrow stream of highly abrasive grit material of a selected particle size range is then directed through a relatively large nozzle under selected high pressure toward the maskant perforations at a very small angle relative to the perforation walls until perforations are formed in the composite material according to the perforation pattern. The perforated sheet produced is particularly adapted for use in sound attenuation structures.
Whereas the above references discuss various sandblasting techniques to wood and/or plastic structures, none of the above references directly address a method or apparatus wherein the grain structure of the wood may be simulated, or at least aesthetically duplicated, in plastic.
A method of fabrication of a sign apparatus needs to be developed wherein the designer of the sign may select different surface textures for different surface areas on the face of the sign body.